Submission #404611

#	Time	Username	Problem	Language	Result	Execution time	Memory
404611		Aryan_Raina	Network (BOI15_net)	C++14	0 / 100	1 ms	204 KiB

net

#include <bits/stdc++.h>
using namespace std; 

#define int int64_t
#define ld long double
#define ar array

const int INF = 1e17;
const int MOD = 1e9+7;

int32_t main() {
   ios_base::sync_with_stdio(0);
   cin.tie(0); cout.tie(0);

   int N; cin >> N;
   vector<int> g[N];
   for (int i = 0; i < N - 1; i++) {
      int a, b; cin >> a >> b; --a, --b;
      g[a].push_back(b); g[b].push_back(a);
   }

   vector<int> leaves;
   function<void(int,int)> dfs = [&](int u, int pu) {
      for (int v : g[u]) if (v != pu) dfs(v, u);
      if (g[u].size() == 1) leaves.push_back(u);
   };

   // leaves are now sorted in tout order
   dfs(0, 0);

   cout << (leaves.size() + 1) / 2 << '\n';

   for (int i = 0; i < leaves.size()/2; i++)
      cout << leaves[i] + 1 << ' ' << leaves[leaves.size() - 1 - i] + 1 << '\n';

   if (leaves.size() & 1) 
      cout << leaves[leaves.size()/2] + 1 << ' ' << leaves[0] + 1<< '\n';
}  
 

Compilation message (stderr)

net.cpp: In function 'int32_t main()':
net.cpp:33:22: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |    for (int i = 0; i < leaves.size()/2; i++)
      |                    ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37